Development of new teaching materials using amylase and protease in digestive juice collected from larvae of the silkworm, Bombyx mori.

Abstract

It was demonstrated that amylase and protease in digestive juice (DJ) collected from the 5th larvae of the silkworm, Bombyx mori, are new promising educational materials in high school biology for deeper understanding of gene expression and enzyme function at the molecular level. The DJ showed to be markedly high alkaline, pH=11.4. Judging from frame reaction, relatively high content of K was present in the DJ as a major ionic element. Optimum reaction pH for amylase and protease was extremely high, indicating highly alkaline enzymes. Both enzyme activities weredifferent among three strains tested: higher activities were detected in 'Daizo' for amylase, and in 'Kinshu x Shouwa' and 'Koishimaru' for protease. Additional characterization of protease was examined as follows: (1) the optimum reaction temperature was over 35°C, (2) the enzyme titer in vivo was estimated to be in the range of 0.27 U ―0.54 U/20μL, (3) the enzyme activity was strongly blocked by AEBSF, a serine-protease inhibitor. Combining with present results and data-baseinformation on protease-encoding cDNA, a new definite teaching program was made up and used for a trial lesson, by which it is possible to lead better understanding of the whole process of protease synthesis and secretion in midgut cells, and protease function in digestive tube as well.